Quasi-steady-state CEST for rapid and quantitative lesion detection in multiple sclerosis at 3T

Area of Science:

• Biomedical Imaging
• Magnetic Resonance Imaging
• Neuroimaging

Background:

• Chemical Exchange Saturation Transfer (CEST) MRI is valuable for multiple sclerosis (MS) diagnosis and remyelination monitoring.
• Quantitative CEST MRI faces challenges with scan parameter variability and long saturation times.
• Optimizing scan efficiency is crucial for clinical applicability.

Purpose of the Study:

• To investigate the utility of quasi-steady-state (QUASS) CEST MRI at 3T to reduce scan time in MS.
• To evaluate QUASS-corrected quantitative measurements for maintaining consistent lesion contrast.
• To assess the impact of QUASS on detecting specific CEST effects in MS.

Main Methods:

• Numerical simulations and in vivo experiments with healthy volunteers and MS patients.
• Application of QUASS processing to CEST MRI data acquired at 3T.
• Isolation of five CEST effects (amide, CEST@2ppm, MT, rNOE, DS) using 5-pool Lorentzian fitting.

Main Results:

• QUASS effectively eliminated saturation time dependence and improved CEST@2ppm detectability in simulations.
• In vivo experiments demonstrated high MS lesion contrast with a 46.7% scan time reduction using QUASS.
• QUASS-corrected CEST revealed decreasing rNOE and MT contrasts with demyelination, while amide decreased in lesions, and CEST@2ppm showed significant reduction in MS lesions.

Conclusions:

• QUASS-CEST MRI offers a faster, robust method for quantitative imaging in MS.
• The technique provides insights into demyelination and protein loss in MS lesions.
• QUASS-CEST holds significant potential for clinical MS diagnosis and treatment assessment.